Executive summary

This report provides an analysis of future Irish climate conditions for the period 2021–2060 based on the outputs from a new regional climate modelling facility located in Met Éireann.

These are the first results from the Met Éireann Regional Climate Model and represent the first steps in an ambitious programme to run an ensemble of simulations that will improve our understanding of climate change and its implications for Ireland, and quantify the uncertainties in the climate projections.

The simulation of the future climate is driven at the boundaries by the output of the Max Planck Institute Global Climate Model with future greenhouse gas concentrations following the moderately increasing concentrations scenario used by the Intergovernmental Panel on Climate Change. Projected temperature changes from the model output show a general warming in the future period with mean monthly temperatures increasing typically between 1.25 and 1.5°C. The largest increases are seen in the southeast and east, with the greatest warming occurring in July.

For precipitation, the most significant changes occur in the months of June and December; June values show a decrease of about 10% compared with the current climate, noticeably in the southern half of the country; December values show increases ranging between 10% in the south-east and 25% in the north-west. There is also some evidence of an increase in the frequency of extreme precipitation events (i.e. events which exceed 20 mm or more per day) in the north-west.

In the future scenario, the frequency of intense cyclones (storms) over the North Atlantic area in the vicinity of Ireland is increased by about 15% compared with the current climate. This is related to the projected general rise in sea surface temperatures. In a practical application of this new data set, a hydrological model was used to assess the impact of climate change on river discharge and local flooding in the Suir catchment area.

The increase in winter precipitation was found to produce a significant increase in the more intense discharge episodes, raising the risk of future flooding in the area.

As part of the climate model validation work, a 40-year simulation of the past climate (1961–2000) wascompleted. The output data complement the archive existing climate observations and, together with the data for the future climate, greatly enhance the scope studies of the impacts of climate change in Ireland.